BACKGROUND OF THE INVENTION To provide the greatest listening pleasure, acoustic loudspeaker meet several requirements. First, a loudspeaker mustaccurately very low frequencies, such as bass notes below Hz, which are felt than heard by most listeners. Secondly, must accurately overtones of high frequencies. Thirdly, aloudspeaker should a relatively flat and phase response over the full of audible frequencies, i. e., fromapproximately Hz to 20, 000 Hz, in order to produce high-fidelity Fourthly, to provide a wide dynamic range, a loudspeaker musthandle signals power sufficient to reproduce low frequencies at loud volumes distortion to the sound or to the speaker.

In to the ideal and phase response characteristics of a loudspeaker, system of multiple loudspeakers should whatever spatial illusions contained in the source material. Forexample, music sources are encoded for stereo reproduction using two channels. Two,spatially-separated and phase-synchronous infinitesimal sources of acoustic energy theoretically provide the best stereo imaging, because such point sources can create the illusion sound originating from any point along aline through both point sources. Therefore, a loudspeaker systemshould as closely aspossible twoinfinitesimally small point sources of acoustic energy.

Because a single driver cannot easily both the frequency range and power handling capability by audiophiles high fidelity sound reproduction, most conventional loudspeaker systemsrely two or more acoustic drivers, or transducers, per channel. driver of a channel isresponsible for reproducing sounds in only apreselected of the audible e. g. , 40 Hz to 200 Hz for a speaker designed for frequencies, also as a"woofer,"or from 3 kHz to 22 kHz for a speaker designed for high frequencies, also as a "tweeter."As more fully explained below, characteristics that optimize an acoustic driver for high frequency response are often the opposite of those that optimize a driver for low response. By utilizing multiple per channel, each driver can be optimized to operate within a selected of the acoustic range. An electrical circuit, known as a crossover network, is used to split energy of the input signal between the drivers, depending on the frequency of the energy in the signal.

Despite widespread acceptance,multi-driver have several drawbacks.

First, crossover networks often distort the electrical signal, introducing distortion into the sound reproduced by the loudspeaker For example, crossover networks naturally phase distortion in incoming signals ; i. e., frequencies are phase shifted with respect to the lower Phase shifting results ina loss of clarity, the music to sound"muddy. "Although networks sometimes employ complex to correct phase distortion, phase-correction circuits can also introduce distortion and often have non-liner Second, multi-driver speaker systems tend to be larger have more components, thus making them more expensive, bulkier andless mobile. a multi-driver does not satisfactorily represent a point source of acoustic energy for a single channel, the full bandwidth of sound reproduced by a channel radiated from multiple points, i. e., point locations each individual driver. Thus, a multi-driver loudspeaker provide ideal stereo imaging.

As noted previously, an acoustic loudspeaker should an infinitesimally small source of acoustic energy, which would ideally in the form of a single acoustic driver. The problems associated with using a single to reproduce high notes with clarity andlow with physical however, are difficult to overcome.

Attempts have been made to accommodate the demands of accurately reproducing both high and low in a single, broad band acoustic driver. For example, U.S. Patent Nos. 3, 983, 337, 4, 115, 667, and 4, 188, 711 to Babb disclose several improvements to the design of an acoustic driver for providing broadband high-fidelity performance. Although drivers employing the techniques disclosed by Babb do have enhanced acoustical in comparison with conventional loudspeaker designs,problems still with using such acoustic drivers to approximate an ideal infinitesimally-small source of acoustic energy.

Although not limited to loudspeaker that employ only asingle acoustic driver, one problem associated with attempting to approximate an ideal infinitesimally- small source of acoustic energy is related the acoustical of the structures used for mounting and enclosing the acoustic driver. An acoustic driver must include mounting structure that rigidly the transducer elements in order to allow transducer to efficiently convert the electrical to a mechanical motion of the driver cone that imparts acoustic energy to the surrounding air. In addition, a conventional loudspeaker must take into account the structure in which the acoustic driver is enclosed, i. e., itsenclosure. Ideally, structures should have a harmonic resonant frequency within the audible spectrum, or the structure will"ring,"which canresult an undesired"coloration"of sound produced by the loudspeaker.

A conventional driver also includes suspension system that surrounds the cone. The suspension system allows cone to vibrate, whereby the mechanical energy in the cone imparts acoustic energy to the surrounding air. A portion of the acoustic energy, however, is imparted to the air behind the cone, thus directing a portion of the reproduced frequency spectrum toward the mounting structure and within the enclosure. to the relatively low of such suspension systems, they are relatively to acoustic energy. The acoustic energy directed rearwardly from the cone can be reflected by the mounting structure or and leak the suspension system, resulting in sound which is slightly due to the delay in the reflected sounds mixing with the sound emanating directly from the driver.

SUMMARY OF THE INVENTION To address deficiencies of the prior art, it is a primary object of the present invention to provide structures for mounting and/or enclosing drivers that result in speakers with improved broad-band frequency response. In the invention allows fidelity loudspeaker enclosures to be formed from materials normally considered unsuitable for loudspeaker enclosures, as sheet metal, wallboard and plastic, in shapes and sizes that have not previously a desirable level of acoustic performance.

Preferred and alternative embodiments of speaker systems having an enclosure and an acoustic driver, which are described below, haveseveral each of which alone in combination with others has as an objective of solving one or more of the previously noted problems and deficiencies of prior art loudspeaker systems. Following is a brief summary of some of these aspects, which summary is intended only to explain the benefits and advantages of various aspects of the several disclosed embodiments and not to limit the scope of the claims.

In with one such aspect of the disclosed a support structure a radiating surface of an audio driver includes frames separated by one or more resilient spacingelements. first and second frames and the spacing element cooperate to attenuate transmission of acoustic energy from the radiating surface to an enclosure which the support structure is mounted. The support structure can be employed advantage in attenuating transmission of undesired frequencies to an enclosure to which the support structure is mounted, particularly high- frequency energies.

In aspect, an enclosure housing at least audio driver includes a "limp"wall that, alone in cooperation with other members of the enclosure, defines cavity immediately surrounding the driver, separate from the remaining interior volume of the enclosure. Thewall functionslike alow passfilter. It a mass and is flexible. It supported within the enclosure that it tends to be displaced by acoustic waves in the bass audio range. The limp wall transmits low acoustic waves into the remaining volume of the enclosure. In words, it tends to move in sympathy with low acoustic waves. Yet, due to the material from which it is constructed and its physical it tends not to move or to vibrate in sympathy with mid to high frequency waves. Rather, the limp wall made of a foam material that tends to absorb such acoustic waves. In to the limp wall some prior art loudspeaker enclosures a layer foam material is applied directly the interior walls the loudspeaker enclosure. Because the layer foam material coupled directly the rigid exterior walls, it does not move as a function of the frequency of the incident acoustic energy. A bass reflex in which a tuned port is coupled with the remaining volume of the enclosure to enhance bass performance, is tunable a lower when a limp wall placed immediately behind the driver. Furthermore, the energy developed by the port is increased without having to increase the volume, and thus also thesize, the enclosure. used in an enclosure does not have a tuned port, known as acoustic suspension, the limp wall lowers frequency cut-off of the acoustic driver, providing bass performance. Thus, the limp wall isparticularly for use with enclosures having a single, broadband, acoustic driver that is intended to operate over the entire audio range, as it heips some of the problems in producing bass frequencies with such a driver.

When an enclosure a given acoustic driver is made smaller, internal acoustic pressure per unit area on the walls the enclosure will increase. Increased pressure will the amplitude of resonance in the walls the enclosure. Walls can be made thicker to stiffen them. However, this actually increases the outer dimensions of the enclosure, thus at least partially the purpose of making the enclosures smaller. overcome this problem, the enclosures of the disclosed embodiments have double layerwalls. Thewalls are attached to form an integral enclosure are formed from an outer layer. outer layer be, for example, medium density fiberboard (MDF) or plastic. inner layer formed of thin, relatively dense and stiff material, as steel, is coupled to the outer layer a resilient, spacing structure. Together, the double layers up less volume a single layer having a thickness necessary to withstand resonating at higher pressures. The resilient structure be, at least part, a foam material that adheres to the inner and the outer layer. foam material also relative movement of one layer the other.

Furthermore, if the foam layer islaid strips to create thin layer air between the inner and outer layers, the air layer tends to act as a resilient dampening structure.

Higher frequency acoustic waves tend to bounce off the inner layer to its mass, stiffness and density. However, to the extent the inner layer would resonate -e. g. by displacement relative to the outer wall by vibration within the wall-the foam material and air layer will such movement and flexing, especially its coupling of materials with different resonant characteristics. Such a double-walled enclosure has an advantage over simply makingwalls a conventional enclosure thicker. Stiffening a wall to increase the resonant frequency. Making a wall more massive tends to lower resonant frequency. Making a wall adds mass and stiffness, resulting a wall has similar frequencies.

Other aspects of the disclosed are directed toward mounting an acoustic driver in an enclose defined by a framed building for example wood framed walls by a material as gypsum board (also to as "wall rock,"and"dry wall"). structures typically poor acoustical qualities, part because of the relatively long between framing members that is spanned by a relatively flimsy material. acoustic pressures of the sound generated by the transducer will to bow the walls, especially lower frequencies, thereby causing loss energy. In aspect, an integrated unit comprised of an acoustic transducer is rigidly to a stiff back plate of a material as steel. back plate a front plate which the transducer is mounted are spaced apart, and an enclosure is defined between the front plate the back plate least in part by a limp wall. Alimp wall, aspreviously explained,couples the low acoustic waves to the wall outside the enclosure by the unit and tends to absorb higher frequency acoustic energy. The back steel plate will not bow or under pressure of the acoustic waves. To prevent undesirable ringing in the back plate, transducer and the back plate be spaced so that, when the unit is installed an opening through one side of a hollow wall, back plate can be coupled the back wall panel a dampening material, as a resilient foam. Another aspect includes structure that may be inserted through an opening in one side of a hole has been cut for insertion of an acoustic transducer. The structure includes chains of linked rigidplates when inserted into a hollow wall between two elongated members, define a rigid enclosure at least some distance from the acoustic transducer. The plates each of the two chains of plates interlock a manner to permit relative articulation that they may be fed through the hole then turned upwardly ordownwardly the wall. two chains are joined by rigid cross members that extend between pairs of plates in the chains. The rigid cross members are joined to the chains with pivoting connections. This allows entire structure to be collapsed feeding through the hole the wall, then expanded so that it wedges between the two sides of the wall.

Joined to each plate a dampening material, as a resilient foam material, that the piates will coupled to the wall panels a resilient coupling dampens any undesirable ringing in the plates andwall panels.

The foregoing has outlined the features and technical of the disclosed structures. Additional and advantages of these structures will be described in reference to the appended drawings, in which : BRIEF OF THE DRAWINGS FIG. illustrates a side, cross-sectional of an acoustic loudspeaker having a first exemplary enclosure for an acoustic driver.

FIG. is a frontal, cross-sectional of the acoustic loudspeaker of FIG. 1, taken along section line in FIG. 1.

FIG. illustrates a side view of an acoustic loudspeaker a second exemplary enclosure for an acoustic driver.

FIG. is a side view of an acoustic loudspeaker having a third exemplary enclosure an acoustic driver.

FIG. 4illustrates cut-away perspective view of the acoustic loudspeaker shown in FIG. 3.

FIG. illustrates a cross-sectional of an exemplary structure for an acoustic driver.

FIG. is a front elevational of a hollow wall a building a front wall panel removed, in which a loudspeaker system is installed.

Fig. 7 is a side cross-section of the hollow wall Fig. 6, showing a pair of rigid plates are erected within the wall.

Fig. 8 is a front elevational of one embodiment of the loudspeaker unit of the loudspeaker shown in Fig. 6, having a front plate is partially removed.

Fig. 9 is a cross-section of the loudspeaker of Fig. 8, taken along section-fine 9-9.

Fig. 10 is a cross-section of the loudspeaker of Fig. 8 taken along section line 10-10.

Fig. 11 is a front elevational of another embodiment of the loudspeaker unit of the loudspeaker system shown in Fig. 6, having a front plate is partially removed.

Fig. 12 is a cross-section of the loudspeaker of Fig. 11 taken along section lines 12-12.

Fig. 13 is a cross-section of another embodiment of a loudspeaker unit like that of Fig. 12, but with a modified front plate.

DETAILED DESCRIPTION Referring to FIG. 1,illustrated a side view of an acoustic loudspeaker 100 having an exemplary enclosure110 an acoustic driver 120. The enclosure 110 has a plurality of walls that define a closed cavity. As illustrated, thewall 105includes a rear wall portion105a, front wall portion105b, top wall portion105c a bottom wall portion105d. Sidewall of the enclosure areillustrated inFIG. The front wall 105b has defined therein an opening through which an acoustic driver 120 is mounted.

During operation, more than one half the acoustic energy generated by the acoustic driver 120 is radiated rearwardly, the enclosure This is due to the relatively small volume the enclosure to the room in which the speaker is placed. Ideally, theenclosure should have a harmonic resonance within the audible frequency spectrum. At mid to high audio frequencies, sound emanating from the enclosure, due to resonance, colors the sound. Furthermore, it also reduces clarity high frequency audio waves are directional. Waves radiating from the enclosure to a listener like are coming from different directions than the acoustic waves emanating forwardly the driver, and they arrive at times.

This spatial andtemporal of the acoustic signal reduces clarity the sound to the listener destroys the signal source model good stereo imaging. As the enclosure is made smaller, pressures within the enclosure with an acoustic driver of a given size. Greater pressures mean more sound leakage through the walls the enclosure greater amplitude of the resonance of the enclosure.

To enhance the acoustical of enclosure the wall is formed of two layers or components ; an outer layer, generally 111, and an inner layer, generally designated 112, coupled at least intermediate spacing element, generally 113. In preferred embodiment, the inner layer is comprised of a plurality panels 112a, 112b, 112c and 112d, on the back, front, top and bottom sides of the enclosure 110,respectively. are slightly smaller in dimensions than the respective back, front, top, and bottom outer layer panels111a, 111 b, 111 c and 111 d, to which they are placed. outer layer panels 111 a, 111 b, 111 c and111 d, with two side panels are shown in Fig. 2, are joined along edges to define the closed of the enclosure 110.

Turning now to FIG. 2,illustrated a frontal, cross-sectional of the acoustic loudspeaker 100 of FIG. The enclosure 110includes aninner layer side panel 112e proximate to outer layer panel 111 e, together form side wall 105e, an inner layer sidepanel 112f to an outer layer sidepanel 111f, together form side wall 105f.Although loudspeaker 100 shown in Fig's 1 and 2 has walls are substantially planar joined at right angles, the principles of the present invention are not limited to a particular enclosure geometry, and may be employed to advantage in enclosures many different sizes and shapes, including enclosures havingplanar walls, non-planar walls, combinations thereof.

Referring now to FIG's 2 and 3, the panels of the inner layer the walls 105 of the enclosure preferably formed of sheets of a relatively stiff and dense material, as steel. 116 further stiffen panels The outer layer panels 111 of the walls are preferably made of a material with a different resonant property, for example conventional Due to the density and rigidity of steel, for example, the inner layer be made relatively thin while still significant amounts of acoustic energy from reaching the outer layer. the enclosure 110 can be made relatively smaller a corresponding increase in the thickness of the walls to deal the effects of greater internal acoustic pressures. The use of steel for the inner wall has the addition of magnetically-shielding the loudspeaker, thus preventing magnetic fields generated by the acoustic driver from interfering with nearby computer or video displays.

Spacing elements are comprised of a material, example foam, that tends not to transmit mechanical at audio frequencies. Rather, the spacing elements tend to dampen mechanical vibrations in the inner layer panels in particular resonance in the inner layer panel a displacement of the inner layer panel relative to the outer layer panel.Similarly, one or more spacing elements 113 couple outer layer panel of each wall to a massive inner layer 112, mechanical vibrations in the outer wall will tendalso be dampened. The spacing elements thus preferably as isolation between the inner and outer walls. induced in one wall to incident acoustic energy are not directly coupled the other wall. different masses and resonant properties of the inner and outer walls in effect, impedance mismatches for transmission of the vibrationsor resonance from one layer another. This multiple-layer wall thus tends to block andreflect into the cavity acoustic audio energy from the driver 120 and to dampen vibrations that tend naturally set up in the panels using a conventional, relatively thickersingle of material construct the wall.

Furthermore, the spacing elements are preferably as strips of foam to define a layer of air trapped in spaces 114 between adjacent inner layer panels 112 and the outer layer panels The strips impede, but do not necessarily the flow air from the spaces 114 as an inner layer 112 moves toward an adjacent outer layer panel Thus, the air layer to impede movement of, and hence dampen mechanical in, outer layer panels. Theair layer also an impedance mismatch at the boundary of the air with the inner layer panel and at the boundary of air with the outer layer panel The mismatches impede, due to the different transmission characteristics of the respective media, transmission of audio frequency acoustic waves from the cavity to outside the enclosure.

Referring now to FIG's and 4, loudspeaker includes enclosure and acoustic driver 120. However, unlike loudspeaker (Fig's 1 and 2), loudspeaker 300 further includes is referred to herein as a"limp wall"arranged closely behind acoustic driver 120. Although addition can be achieved by use of the limp wall with enclosure 110, it can also used to advantage in conventional enclosures. The benefits of the limp wall include of mid and high audio frequency acoustic waves emanating from the rear of acoustic driver 120, while bass or low audio frequency acoustic waves. Thus, undesirable of mid to high audio frequency acoustic energy within the enclosure be reduced, while the bass or low audio frequency performance.

In theillustrated exemplary the limp wall a first and a second segment, designated respectively and 312, for forming, in cooperation with sidewalls and 105f, a complete enclosure the rear of the acoustic driver 120. The first segment 311 is suspended from the upper wall 105c. It permitted to move toward and away from the acoustic driver. In it is permitted to swing much like avertically curtain. The vertical 311 is hung using a hinge that permits the segment to swing toward and away from the acoustic driver 120. This hinge, for example, formed using adhesive tape 315. The limp wall's horizontal 312 functions to fully enclose acoustic driver 120, while freedom of movement for the vertical 311. The horizontal extends generally perpendicularly from the wall the vertical 311. The segment is attached one side to the front wall with a hinge that allows segment to pivot freely and away from the driver. Adhesive tape 315 is, for example, used to form the hinge. Vertical and horizontal of the limp wall joined, similarly, a hinged connection formed by another piece of adhesive tape 315. The vertical horizontal segments are therefore able pivot with respect to each other, generally along axis that is parallel the axes of the other hinged connections. Both limp wall 311 and 312 are sufficiently flexible to allow segment 312 to bend upwards as vertical segment 311 moves away from the driver. This flexibility also allows segments to bow as the vertical moves toward the driver 120 under certain conditions : namely, whenlow frequencies the limp wall swing or move in sympathy with movement of the acoustic driver 120. Edges of the limp wall areclosely the inside surfaces of sidewalls and 105f of the enclosure 110, and can brush the walls desired.

The limp wall reflects, and absorbs incident acoustic energy radiated by the driver 120. Preferably, the wall made of material, as foam, that tends to absorb relatively high frequency energy than low energy. The limp wall preferably also a relatively low per unit area, or density, and relatively low spring forces. A wall of foam tends to have relatively low and spring forces.

Furthermore, by making the wall limp, opposed to tightly a layer foam behind the driver, the middle of portion of the wall isallowed move and thereby resonate. Yet, the wall cooperates the enclosure define a much smaller enclosure that tends to prevent acoustic energy, particular at low from leaking the limp wall. the wall hung or held position by attaching it, inpart, to rigid surfaces in a manner that tends not to interfere with the movement or <BR> <BR> <BR> <BR> <BR> <BR> <BR> vibration of the middle of the wall atlower such as by using the previously hinges. The limp wall to attenuate, rather than merely reflect, acoustic energy in the middle high portions of the audio range that is radiated rearwardly the acoustic driver 120, while in sympathy with the driver.

To further enhance the absorption characteristics of the limp wall without interfering with its resonance, vertical wall 311 and horizontal wall segment 312 are each constructed of two, relatively thin andrelatively denselayers foam 314a and 314b, separated by a plurality of spaced-apart, resilient, spacingelements the form of relatively less and thicker foam 313. The resulting tends better to resist vibration or resonance at mid to high audio frequencies and to attenuate acoustic energy associated with those frequencies. However, as compared to a single, relatively thick layer foam, this dual-layer tends to have a lesser springforce and mass. Thus, it accomplishes attenuation of mid to high audio frequency acoustic energy while freedom to move with respect to the acoustic driver 120.

The operation of the limp wall is analogous to a low-pass filter in an electronic circuit to attenuate high frequencies while transmittinglow frequencies.

It willat least acoustic energy in the mid and high audio frequencies, while a flexible around the acoustic driver that will"air lock"to, or be coupled the motion of the speaker cone at low frequencies (e. g., 30 to 100 Hz). However, because acoustic waves at low frequencies tend to move or displace entire limp wall, therelatively low of the limp watl hinged movement allows to function much like additional cone mass at low audio frequencies. In tuned port system, for example, the energy developed by the port is increased to the extent the system is undamped. With addition of the limp wall mass to the mass of the acoustic driver cone, the whole can be tuned to lower frequencies.

Referring now to FIG. a corrugated limp wall can be used in place-of the straight limp wall of FIG. Corrugated limp wall behaves in a manner similar that of the straight limp wall However, the corrugations allow greater range of movement of the limp wall and limp wall 311.

FIG. 5illustrates across-sectional of an exemplary mounting structure 500 for an acoustic driver. Acoustic driver 505 includes an electro-mechanical transducer structure is comprised of magnet structure 509 and a coil The transducer drives a diaphragm in the shape of a cone 503. The cone vibrates the air, creating acoustic waves. The mechanical of the coil and cone 503 moving tend to be transmitted to the mounting structure which they are is suspended through suspension 507. A conventional structure is typically as by stamping, from of a relatively thinmetal. a structure tends to resonant at certain audio frequencies, which can be perceived as a"ring."The ringing of the mounting structure is undesirable such ringing can undesirably"color"the of the loudspeaker.

In embodiment illustrated, mounting structure 500 includes first, or inner, frame 511, a second, or outer, frame 512, and at least oneresilient spacing element. spacing element designated 513, and is intermediate to, and couples, the first frame 511 and the second frame 512. The inner frame is essentially "nested"within the outer frame 512. In theexemplary the inner and outer frames 511 and 512 are mechanically coupled screws 510 to a magnet portion 509 ofthe acoustic driver Screws 510 may include asleeve portion51 Oa thatallows the inner and outer frames 511, 512, to"float"relative one another. The resilient spacing elements are made from, for example, foam material is connected withadhesive to the inner and outer frames.

FIG's 6-13illustrate aloudspeaker that uses for an enclosure ahollow structural of a building, boat, automobile g. trunk), the like, than a specially cabinet as shown in FIG's 1-5.The loudspeaker systemwill be explained referenced to a hollow wall a building.

Referring now to FIG. acoustic driver 120 is mounted in a hollow wall structure 600 of a building. Thehollow wall 600 is formed of a front panel and a back panel joined to a frame. In illustrated embodiment, these panels are made from conventional drywall. other types of material could used to enclose the frame. A conventional framingincludes use of spaced, elongated frame members, to which wall such as dry wall (ie. board or sheet rock), wood paneling or plaster isjoined. In theillustrated exemplary these frame members include wall 606 and 608. The front and back panels 602 and 604 and the wall 606 and 608 define a hollow 610. The acoustic speaker may also be mounted in a ceiling floor cavity, among other hollow within a building.

The acoustic transducer 120 is mounted in an opening defined in a rigid or stiff front plate made of, for example, steel. front plate set into an opening cut in the front panel The front plate is one component of an integrated loudspeaker unit 614. Several different embodiments of this integrated unit are described in connection with FIG's 8-12.

To enhance further the acoustic performance of the hollow 610, it is lined with a plurality of pairs 615 of spaced apart, rigid plates. Theplates made, for example, from steel. Only front plate of each pair 615 is visible in FIG. One of the plate 615 is shown in elevation the side in FIG. Referring now only to FIG. front plate and back plate are connected by at least rigid cross member. Two such rigid cross members 620 are illustrated, although one centered cross member or a plurality of cross members can be used. One end of each of the at least rigid cross members is connected by pivoting joint to the front plate 616a. The other end of each of the at least rigid cross members is connected to the rear plate by another pivoting joint. In theillustrated hinges 622 form the pivoting joints.

The purpose of the one or more cross members are to allow theplate 615 to form a rigid enclosure the cavity 610. With aid of the pivoting connections or other structure that allows theplates be collapsed then spread apart with a rigid connection between them, the plate can be collapsed insertion through the opening in the front wall panel and positioning within the cavity 610. The broken lines inFIG. indicate the plate in a collapsed Erecting the rigid connection between the plates bypulling one plate relative the other causes the two plates wedge between the front panel and rear panel thereby securing the position of the plate within the wall. Theresulting provides a rigid, stiff lining cavity 610 that will not to bow or to move under pressure of the low frequency acoustic waves within the cavity area between the plates.

Referring now to FIG's and 7, each steel plate iscoupled inside surfaces of the wall panels and 606 through dampening members 618. In preferred embodiment, the dampening member is formed from a resilient foam material as DuPonf 4318, is attached to the plate an adhesive. The purpose of the resilient members is to provide dampening of any higher frequency ringing that may develop in a steel plate. because of the rigid connection between the plates, acoustic waves at lower frequencieswill not to move the plates.

Referring now only toFIG. to facilitate installation a plurality of plate pairs 615, they may be linked form a chain that, when collapsed, be fed through the opening in the front panel that has been formed for mounting of an acoustic driver in a hollow of a building the like. In theillustrated embodiment, a pivotable is made between adjacent plates a hooked-shaped tab. Each plate includes, one end, one or more hooked-shaped tabs 622. At the end opposite of the one or more tabs, each plate one or more corresponding slots Each slot <BR> <BR> <BR> <BR> is sized and positioned to allow tab of one plate be inserted into the slot of another plate shifted to one side to catch the edge of the slot. a linked chain is dropped, for example, the opening in front panel 602of wall 600, pullingone of the two plates of the plate nearest the opening will each of the other plate to erect.

FIG's 8-13illustrate embodiments of the integrated loudspeaker unit 614 (see FIG. This loudspeaker unit is an integrated structure that can be inserted into an opening formed in an enclosure, whether it is cabinet or other hollow The unit includes an acoustic driver mounted within a space enclosed by a combination of rigid walls anda"limp wall"structure. rigid walls movement and bending under high acoustic pressures associated with low acoustic waves. The limp wall structurecouples lower acoustic power to the air mass within a cavity 610 but tends to absorb middle and higher frequency acoustic waves in the audible range.

The exemplary embodiment illustrated in FIG's 9 and 10 of the loudspeaker unit 614 includes rigid front plate The rigid front plate isrigidly to a rigid back plate The rigid connection is made by four steel 814. Other types of rigid connections could used. However, the posts allow good range of motion for the limp wall The front and back plates define space 804 between the two plates. In illustrated embodiment, rigid black 802also as a heat sink for the acoustic driver 120. The back of the acoustic driver, which is a magnet assembly, is thermally coupled the back plate. rear of the back plate, best seen in FIG. includes a plurality of fins to increase the surface area for heat dissipation. The fins, when closely against back panel as shown in the figures, define chimney-like that promote the flow convention currents from the lower of the cavity 610 below the 614, into an upper part area of the cavity above the unit. The currents of air are heated as they pass by the rear plate and <BR> <BR> <BR> <BR> then cool the upper part of the cavity. The cooler returns to the lower of the cavity 610 between area defined by the sides of unit 614 and studs 606 and 608, respectively. Dampening members 816 couple back plate to the rear panel 604 of the wall 600 for purposes of attenuating any resonance or ringing that might set up in back panel or back plate 802.

The space 804 is enclose, the illustrated embodiment, on the top, bottom, left right sides by a limp wall The limp wall structureincludes two vertically straight limp walls and 808 on the left right sides, and two corrugated or accordion-shaped limp walls and 812 on the top and bottom. The limp walls joined to each other with pivoting joints. The pivoting joints are preferably formed using adhesive backed tape 813.

The straight limp wall is constructed of two, relatively thin and relatively dense layers of foam 806a and 806b, separated by a plurality of spaced-apart, spacing elements in the form of relatively less and thicker foam strips 806c. Similarly, the straight limp wall is constructed of two, relatively and relatively denselayers of foam 808a and 808b, separated by a plurality of spaced-apart, elements in the form of relatively less and thicker foam strips 808c. This limp wall structure tends to resist vibration or resonance at mid to high audio frequencies and to attenuate or dampen acoustic energy associated with those frequencies. However, as compared to a single, relatively thicklayer foam, this dual-layer tends to have a lesser spring force and mass. Thus, it accomplishes attenuation of mid to high audio frequency acoustic energy while freedom to move. The corrugated limp walls are made from a single layer ofrelatively foam. The corrugations allow greater range of expansion and contraction of the limp wall structure.

The front of the loudspeaker unit 614 also a diffusion ring 902. The round edge of the diffusion ring tends to scatter acoustic waves. The scattering lessens the"boomy"sound and standing waves that would result from acoustic energy reflecting the front wall panel 602.

Referring to FIG's alternate exemplary of loudspeaker unit 614 (FIG. are illustrated. The embodiments shown in FIG's are the same as the embodiment shown in FIG's except for the following differences. In the embodiment shown in FIG's and 12, the top corrugated limp wall 810(FIG's and 9) is replaced with a rigid wall and the heat sink rear plate 802(FIG's and 9) is replaced with a flat rigidplate 1104.In thealternate shown in FIG. the front plate includes integral surfaces 1302 around the acoustic driver 120.

These surfaces cause the same type of diffusion of the acoustic waves as the diffusion ring 902 (FIG's Therefore, use of a diffusion ring is not necessary. The rigid wall 1102 provides not only rigid connection between the front and rear plates and 1104, but it also acoustic energy from the driver 120 downwardly into the wall.

These embodiments are examples of how rigid walls be added and/or placed to direct acoustic energy in particular directions, rather than in all within cavity 610.

Although the present invention and its advantages have been described with reference to specific embodiments, various modifications, substitutions and rearrangements to the specific embodiments disclosed herein can be made without departing from the scope of the invention defined by the appended claims. Such alternative embodiments are intended to be within the claims recited hereinafter.

What is claimed is :